Finally, a Bright Future for Landsat
By Dr. Shaida Johnston
In November 2008, I attended one of the most positive land remote sensing symposia conducted in years. The pall that had fallen over the community since 2003 and the fog of uncertainty over the future of the program are finally lifting. There is a new spirit of optimism in the air for land remote sensing and it was evident at the 17th William T. Pecora Memorial Remote Sensing Symposium that took place in Denver, Colorado. From the opening session, which celebrated the vision of William Pecora and Stewart Udall in a poignant video entitled An Idea That Worked, to the technical sessions describing the expected improved performance of the Landsat Data Continuity Mission (LDCM) over that of Landsat 7, the positive energy was palpable.
Some of the excitement stemmed from the celebratory looks to the past honoring the visionaries who initiated the civilian land remote sensing program, and from the technological achievement of Landsat 5 reaching its 25th year of continuous on-orbit operations and observations. The rest of the excitement came from looking forward. After many years of indecision about the next Landsat mission – first looking at a commercial data buy, then a public-private partnership, then a Landsat instrument on an NPOESS platform – we now finally have a funded, free-flying satellite mission that is being developed and looking quite promising. The ‘cherry on top' for the week, which delighted me and many other users of Landsat data, was the announcement by the U.S. Geological Survey (USGS), that all Landsat data now can be downloaded for free from the archive. From the inception of this program on Oct. 1, 2008 through Jan. 9, 2009, over 225,000 scenes have been downloaded from the Landsat 7 archive.
Figure 1 Belize, South America, taken by Landsat 5. Image courtesy of USGS.
In looking back and honoring the work of the pioneers in the field, one realizes that the ideas of the visionaries have come to fruition through not just hard work, but also perseverance in the face of almost constant programmatic turmoil. The symposium is named after Dr. Pecora who, along with Secretary of Interior Stewart Udall, envisioned a civilian Earth observing system that in 1966 was announced as Project EROS – Earth Resources Observation Satellites. They imagined government-funded satellites carrying remote sensing instruments as a public good, the data from which would be openly distributed and used to gather facts about the natural resources of our planet.
The 1966 announcement stimulated a partnership between NASA, the Department of Interior, and USGS, that resulted in the 1972 launch of the first Earth Resources Technology Satellite (ERTS), later named Landsat 1. The first Pecora Award was presented in 1974, two years after William Pecora's untimely death at age 59, just a few days before the launch of the first ERTS.
It was both in looking back at the contributions of many and in looking toward the future of land imaging that so much optimism and good will were generated by symposium attendees. The week-long event reflected a pride that comes from a program celebrating 40 years of success and a future bright with a new satellite development effort, new data distribution policies, and plenty of new applications.
It is through such longevity that applications have continued to flourish in areas related to human security. USDA's crop monitoring program and Foreign Agricultural Service (FAS) continue to generate crop predictions that focus policy makers and aid agencies on issues of food security. USAID uses their crop predictions for the African continent to anticipate famine when crop yields are low, allowing food aid to be planned and sent in a timely manner.
Climate change researchers also benefit from the continuity of the program and its long-term archive. Direct change techniques comparing multi-temporal Landsat scenes allow scientists to discover and highlight environmental security issues associated with phenomena such as desertification and deforestation, and those stemming from changes in land use and fresh water resources. Many technical papers were presented highlighting these applications, which of course is the main purpose of the symposium. The celebrations were just a plus this year.
Figure 2 Lake Powell, Utah, taken by Landsat 7. Image courtesy of USGS.
I personally, through the Landsat Legacy Project – a project dedicated to writing the history of the Landsat program as seen through the lenses of technology change and the evolution of the satellite concept into a true global observing system – was elated to interview a few of the early pioneers of the ERTS program, capturing their oral histories on video for posterity and future historians. Those interviewed included past Pecora Award winners such as John DeNoyer, Al Watkins, and Vince Salomonson, and instrument engineer Virginia Norwood, whose ‘banging mirror' design has proven to be the on-orbit workhorse of the Landsat program. The programmatic struggles and technical innovations and risks that marked the ERTS era provide a backdrop for the lessons being learned today for LDCM and the future of land imaging.
The 25th anniversary celebration for Landsat 5 on the final evening included, not just symposium attendees, but also the operations teams, and engineers from then General Electric, now Lockheed Martin, who came to celebrate the engineering marvel that Landsat 5 has become. Albeit, one can also point to Landsat 5's longevity as a contributing factor to the indecision about launching LDCM. This indecision will, more than likely, break the continuity of the program, since it will take a few years for LDCM to be launched and operable, and meanwhile, the currently operating Landsat satellites could become inoperable at any time.
Decision makers tend to look at Landsat 5's on-orbit life with the expectation that others will match it, rather than recognizing it for the exceptional engineering feat that it is. Still, you could feel the pride in the room, and it was well earned.
Dr. Shaida S. Johnston is a Science and Technology Policy Specialist in remote sensing, Earth sciences, physics, global space systems, and international environmental treaties with complementary technical expertise in science data systems, Earth observation data applications, systems engineering and acquisition, program management and operations of space systems. She has provided her technical expertise to various federal agencies from the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) to North American Aerospace Defense (NORAD) and the Federal Aviation Administration (FAA).
Dr. Johnston holds a Ph.D. from the George Washington University, Washington, D.C. and M.S. and B.S. degrees in aerospace engineering and physics respectively, from University of California, Los Angeles. She has published in both technical and policy journals. She is based in Falls Church, Va. and can be reached at email@example.com.